Safety driving connection



J. P. MARTIN 1,795,258

SAFETY DRIVING CONNECTION March 3, 1931.

Original Filed March 5, 1927 Patented Mar. 3, I931 UNITED STATES.

PATENT rice TER IRONWORKS, INc., 033 LANcAsTEnrENNsYLvANIA 1 Y SAFETY DRIVING CONNECTION Original application filed March 5, 1927, Serial No. 173,028. Divided and this application filed February I 16, 1929. Serial No. 340,391.

-This application is a-division ofmy copending application, Serial No. 173,028, filed March 5, 1927. 5' i I i The invention forming the subject matter of this application is asafety driving connection adapted to be interposed between a shaft, and means for-driving the shaft in order to permit severance of the driving connection between the shaft and the driving means whenever any force resisting rotation of the shaft exceeds a predetermined value;

The invention is particularly adapted for use in automatic brick machines of the type disclosed in my said application. In the operation of this type of machine, a's'eries of brick mold boxes are, at one stage of the operation, rotated in a sand box by brackets rigidly connected to said shaft. If, at any time, any ofthese molds should become jammed in the sander, itbecomes necessar in orderto avoid serlous damage to the who e 7 machine, to make provision for immediately a radial arm fixed tosaid shaft.

and arm are provlded with holes adapted to register with each other and to receive a severing the driving connectionbetween the shaft and the means for driving 11:.

In the prior machines,the jamming of the part of the mechanism shown in Fig. 1;

molds in the sander or receiving mechanism of this type of machine is taken care of by mounting .a drive gear rotatable freelyv on the sander shaft'and in lateral contact with The gear shear pin in order to impart the rotation of the gear, through the radial arm, to the The'shear pin is generally sander shaft. made of material sufficiently hard to hold the radial arm in driven connection with the driving gear under normal working conditions only, and to shear just as soon as the molds become jammed in the sander or re ceiver, in order to prevent serious injury to the machine as a whole.

' In the old form of safety shear connection between the drive gear and shaft, when the shear pin breaks and the machine is stopped to removethe jammed mold or other obstruction, it is necessary always to bring the radial arm and drive gear into that exact relativeposition in which the shear pin holes register exactly. This operation nearly always necessitates someones getting down'into the sand pit and working the shaft 'backwardly and forwardly until the shear pin holes are broughtinto exact registration. This is evidently an arduous, time consuming and costly apparent as the detailed description thereof proceeds. 7 In the drawings: Fig. 1 1s a fragmentary sectional elevation of the sander part of an automatic brick machine to which this invention is adapted to be applied;

F 1g. 2 1s a fragmentary. end elevation of particularly ig; 3 is a fragmentary sectional elevation of the shaft driving mechanism forming this invention; A

Fig. 4t is a sideelevation of the mechanism shown in Fig. 3; Fig. 5 is a vertical section taken on the line 55 of Fig. 3; I

Fig. 6 is side elevation of the mechanism shown in'Figs. 3 and I; and I Fig. 7 is an exploded perspective view of the shear plate arm for connecting the driving'gear to the driven sander shaft. As shown in Figure 1, the invention. is adapted particularly for use in. an automatic brick machine including supporting framework 1 on which is mounted a sprocket wheel 2'rotated on a stub shaft 3 by suitable'gearing, forming no part of the present invention.

engage with a sanded mold 8, in a certain cycle of operation of the machine, and to raise this mold 8 along the arcuate guide plate 9 onto the receiver plate 10, which drops in timed relation to the movement of the mold in position to receive themold.

The shaft 6, by suitable gearing (not shown) drives the counter shaft 11, having secured thereto the substantially triangular frame 12 for moving the molds 8 through the sander box 18 into position to beengargec l by plate 1lprojecting from the cam member 7.

In order to transmit the rotation of the sprocket wheel 5 to the shaft 6, the hub 15 of the wheel 5 is provided with a radial arm 16 formed integral with said 'hub; A sleeve L7 is keyed to the shaft 6 and is adapted to be adjustably secured to said shaft by a set screw 18 screwthreaded through the sleeve and engaging the key 19.

An arm 20 extends radially from said sleeve .17, and is provided at its outer end with a lug 21 extending laterally from and perpendicularly to said arm. The lug n1 is provided with rabbets 22 and .23, to form a spacing tongue 2% on the opposite sides of which the steel shear plates 25 and 26 are bolted or otherwise suitably secured.

A hardened steel shear plate 27 has one end thereof pivoted between the plates 25 and 26, to swing about the pivot bolt 28 toward and from the tongue 24. provided with an aperture29 adapted to register with apertures 30 and 81, formed in'the plates 25 and 26, respectively; and a shear pin 32 of relatively soft metal is inserted in the apertures 29, 30 and 31 when theseapertures are in registry with each other.

As will be obvious from inspection of the drawing, when the shear plate 27 is secured by the shear pin 32 between the plates 25 and 26, the plate 27 will be in the path of movement of the arm 16. The contact 'between the arm 16 and the free end of shear plate 2 7 will cause the shaft 6 to be rotated by the sleeve 17 in the same direction as the sprocket wheel 5 is rotated by the sprocket chain 1.

'1 he shear pin 32 is made of such material that under normal operation of the machine, it will hold the shear plate 27 locked between the plates 25 and 26, and will cause the shaft 6 to be rotated along with the sprocket 'wheel 5. As soon, however, as one of the molds 8 becomes jammed in the sander mechanism, the shear plate 27 will sever the shear pin 32 and permit the shaft 6 to stop, even though the sprocket wheel 5 continues to rotate there- After the jammed mold 8 or other obstruction shall have been removed from the machine, it only becomes necessary to swing the plate 27 between the plates 25 and 26 into the path of movement of the arm 16, and to pin the plate 27 to the plates 25 and 26 by This plate 27 is.

a new shear pin 32. It does not become necessary, at any time, to aline or register the arm 20 with the arm 16, as all that is required is to ensure the positioning of the shear plate 27 in the path of rotation of the radial arm 16, in order to transmit the rotation of said arm to shafts 6 and 11.

lVhat I claim is: 7

1. In a machine, a shaft, a gear rotatable thereon, and having a hub integral therewith, .an arm extending from said hub and having an edge substantially parallel to a diameter of said shaft-,'a-second-arm fixed tosaid shaft and extending radially therefrom, a pair of steel plates secured to the outer end of said second arm and extending beyond said outer end to form a recess, a steel plate having one end pivoted between said pair of plates atone end thereof and adapted when positioned in said recess to have its free end contact with the said edge.

2. In a machine, a shaft, a gear rotatable thereon, and having an arm fixed thereto, said arm havin an edge parallel to a diameter of said shaft, a second arm fixed to said shaft adjacent the first named arm, a rod p'iv oted at one end to said second arm and extending parallel to said shaft with one of its sides in driven contact with the said edge, and shearable means engaging said arm and plate to hold the latter in driven engagement with said edge.

3. In. a machine, a sha'ft,'a sprocket wheel rotatable on said shaft, means for rotating said wheel, an arm fixed to said wheel and having an edge'parallel to a diameter of said shaft, a second arm fixed to said shaft and having a recess at the free end thereof. a plate seated in said recess and having an edge thereof in driven contact with the said edge of said plate, and shear-able means for bold ing said plate seated in said recess.

l. In a machine, rotatable driving and driven members, one of said members having a shear device pivot ally mounted to move substantially tangentially to the direction of rotation of said member in yielding to an overcon'iing force, the other member bein engageable with said shear device whereby, normally, said members rotate together.

5. In a machine, rota-table driving and driven members, one of said members having a shear device including a blade hingedly supported to swing in a plane tangential to the direction of rotation of said, member, a shear pin normally inhibiting the swinging of said blade, means carried by the other member engageable with said blade stressing it in the direction in which it is adapted to swing, said shear v pin havinga strength value permitting it to break when a predetermined magnitude ofsaid stress is exceeded.

6. In a machine, a shaft, an imperforate arm fixed to said shaft and extending radially therefrom, a second imperforate arm rotatable freely on said shaft, means for r0- tating said second arm on said shaft, and a pin extending substantially parallel to said shaft from the first named arm to contact with an edge of the other arm and thereby rotate said shaft.

In testimony whereof I afiix my signature.

JAMES PRANGLEY MARTIN. 

